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Subject[PATCH v3 2/8] platform/x86: dell-smbios: Introduce a WMI-ACPI interface
Date
The driver currently uses an SMI interface which grants direct access
to physical memory to the firmware SMM methods via a pointer.

Now add a WMI-ACPI interface that is detected by WMI probe and preferred
over the SMI interface.

Changing this to operate over WMI-ACPI will use an ACPI OperationRegion
for a buffer of data storage when SMM calls are performed.

This is a safer approach to use in kernel drivers as the SMM will
only have access to that OperationRegion.

As a result, this change removes the dependency on this driver on the
dcdbas kernel module. It's now an optional compilation option.

When modifying this, add myself to MAINTAINERS.

Signed-off-by: Mario Limonciello <mario.limonciello@dell.com>
---
MAINTAINERS | 6 ++
drivers/platform/x86/Kconfig | 14 ++--
drivers/platform/x86/dell-smbios.c | 128 ++++++++++++++++++++++++++++++++-----
drivers/platform/x86/dell-smbios.h | 15 ++++-
4 files changed, 138 insertions(+), 25 deletions(-)

diff --git a/MAINTAINERS b/MAINTAINERS
index 08b96f77f618..6d76b09f46cc 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3990,6 +3990,12 @@ S: Maintained
F: drivers/hwmon/dell-smm-hwmon.c
F: include/uapi/linux/i8k.h

+DELL SMBIOS DRIVER
+M: Pali Rohár <pali.rohar@gmail.com>
+M: Mario Limonciello <mario.limonciello@dell.com>
+S: Maintained
+F: drivers/platform/x86/dell-smbios.*
+
DELL SYSTEMS MANAGEMENT BASE DRIVER (dcdbas)
M: Doug Warzecha <Douglas_Warzecha@dell.com>
S: Maintained
diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index 1f7959ff055c..415886d7a857 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -92,13 +92,17 @@ config ASUS_LAPTOP
If you have an ACPI-compatible ASUS laptop, say Y or M here.

config DELL_SMBIOS
- tristate
- select DCDBAS
+ tristate "Dell SMBIOS calling interface"
+ depends on ACPI_WMI
---help---
- This module provides common functions for kernel modules using
- Dell SMBIOS.
+ This module provides common functions for kernel modules and
+ userspace using Dell SMBIOS.
+
+ If you have a Dell computer, say Y or M here.

- If you have a Dell laptop, say Y or M here.
+ If you have a machine from < 2007 without a WMI interface you
+ may also want to enable CONFIG_DCDBAS to allow this driver to
+ work.

config DELL_LAPTOP
tristate "Dell Laptop Extras"
diff --git a/drivers/platform/x86/dell-smbios.c b/drivers/platform/x86/dell-smbios.c
index e9b1ca07c872..4472817ee045 100644
--- a/drivers/platform/x86/dell-smbios.c
+++ b/drivers/platform/x86/dell-smbios.c
@@ -4,6 +4,7 @@
* Copyright (c) Red Hat <mjg@redhat.com>
* Copyright (c) 2014 Gabriele Mazzotta <gabriele.mzt@gmail.com>
* Copyright (c) 2014 Pali Rohár <pali.rohar@gmail.com>
+ * Copyright (c) 2017 Dell Inc.
*
* Based on documentation in the libsmbios package:
* Copyright (C) 2005-2014 Dell Inc.
@@ -22,9 +23,15 @@
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/io.h>
-#include "../../firmware/dcdbas.h"
+#include <linux/wmi.h>
#include "dell-smbios.h"

+#ifdef CONFIG_DCDBAS
+#include "../../firmware/dcdbas.h"
+#endif
+
+#define DELL_WMI_SMBIOS_GUID "A80593CE-A997-11DA-B012-B622A1EF5492"
+
struct calling_interface_structure {
struct dmi_header header;
u16 cmdIOAddress;
@@ -33,12 +40,14 @@ struct calling_interface_structure {
struct calling_interface_token tokens[];
} __packed;

-static struct calling_interface_buffer *buffer;
+static void *buffer;
+static size_t bufferlen;
static DEFINE_MUTEX(buffer_mutex);

static int da_command_address;
static int da_command_code;
static int da_num_tokens;
+struct wmi_device *wmi_dev;
static struct calling_interface_token *da_tokens;

int dell_smbios_error(int value)
@@ -60,13 +69,15 @@ struct calling_interface_buffer *dell_smbios_get_buffer(void)
{
mutex_lock(&buffer_mutex);
dell_smbios_clear_buffer();
+ if (wmi_dev)
+ return &((struct wmi_calling_interface_buffer *) buffer)->smi;
return buffer;
}
EXPORT_SYMBOL_GPL(dell_smbios_get_buffer);

void dell_smbios_clear_buffer(void)
{
- memset(buffer, 0, sizeof(struct calling_interface_buffer));
+ memset(buffer, 0, bufferlen);
}
EXPORT_SYMBOL_GPL(dell_smbios_clear_buffer);

@@ -76,7 +87,36 @@ void dell_smbios_release_buffer(void)
}
EXPORT_SYMBOL_GPL(dell_smbios_release_buffer);

-void dell_smbios_send_request(int class, int select)
+static int run_wmi_smbios_call(struct wmi_calling_interface_buffer *buf)
+{
+ struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
+ struct acpi_buffer input;
+ union acpi_object *obj;
+ acpi_status status;
+
+ input.length = sizeof(struct wmi_calling_interface_buffer);
+ input.pointer = buf;
+
+ status = wmidev_evaluate_method(wmi_dev, 0, 1, &input, &output);
+ if (ACPI_FAILURE(status)) {
+ pr_err("%x/%x [%x,%x,%x,%x] call failed\n",
+ buf->smi.class, buf->smi.select,
+ buf->smi.input[0], buf->smi.input[1],
+ buf->smi.input[2], buf->smi.input[3]);
+ return -EIO;
+ }
+ obj = (union acpi_object *)output.pointer;
+ if (obj->type != ACPI_TYPE_BUFFER) {
+ pr_err("invalid type : %d\n", obj->type);
+ return -EIO;
+ }
+ memcpy(buf, obj->buffer.pointer, input.length);
+
+ return 0;
+}
+
+#ifdef CONFIG_DCDBAS
+static void run_smi_smbios_call(struct calling_interface_buffer *buf)
{
struct smi_cmd command;

@@ -85,12 +125,28 @@ void dell_smbios_send_request(int class, int select)
command.command_code = da_command_code;
command.ebx = virt_to_phys(buffer);
command.ecx = 0x42534931;
-
- buffer->class = class;
- buffer->select = select;
-
dcdbas_smi_request(&command);
}
+#else
+static void run_smi_smbios_call(struct calling_interface_buffer *buf) {}
+#endif /* CONFIG_DCDBAS */
+
+void dell_smbios_send_request(int class, int select)
+{
+ if (wmi_dev) {
+ struct wmi_calling_interface_buffer *buf = buffer;
+
+ buf->smi.class = class;
+ buf->smi.select = select;
+ run_wmi_smbios_call(buf);
+ } else {
+ struct calling_interface_buffer *buf = buffer;
+
+ buf->class = class;
+ buf->select = select;
+ run_smi_smbios_call(buf);
+ }
+}
EXPORT_SYMBOL_GPL(dell_smbios_send_request);

struct calling_interface_token *dell_smbios_find_token(int tokenid)
@@ -170,10 +226,43 @@ static void __init find_tokens(const struct dmi_header *dm, void *dummy)
}
}

-static int __init dell_smbios_init(void)
+static int dell_smbios_wmi_probe(struct wmi_device *wdev)
+{
+ /* no longer need the SMI page */
+ free_page((unsigned long)buffer);
+
+ /* WMI buffer should be 32k */
+ buffer = (void *)__get_free_pages(GFP_KERNEL, 3);
+ if (!buffer)
+ return -ENOMEM;
+ bufferlen = sizeof(struct wmi_calling_interface_buffer);
+ wmi_dev = wdev;
+ return 0;
+}
+
+static int dell_smbios_wmi_remove(struct wmi_device *wdev)
{
- int ret;
+ wmi_dev = NULL;
+ free_pages((unsigned long)buffer, 3);
+ return 0;
+}

+static const struct wmi_device_id dell_smbios_wmi_id_table[] = {
+ { .guid_string = DELL_WMI_SMBIOS_GUID },
+ { },
+};
+
+static struct wmi_driver dell_wmi_smbios_driver = {
+ .driver = {
+ .name = "dell-smbios",
+ },
+ .probe = dell_smbios_wmi_probe,
+ .remove = dell_smbios_wmi_remove,
+ .id_table = dell_smbios_wmi_id_table,
+};
+
+static int __init dell_smbios_init(void)
+{
dmi_walk(find_tokens, NULL);

if (!da_tokens) {
@@ -181,34 +270,39 @@ static int __init dell_smbios_init(void)
return -ENODEV;
}

+#ifdef CONFIG_DCDBAS
/*
* Allocate buffer below 4GB for SMI data--only 32-bit physical addr
* is passed to SMI handler.
*/
buffer = (void *)__get_free_page(GFP_KERNEL | GFP_DMA32);
+ bufferlen = sizeof(struct calling_interface_buffer);
+#else
+ buffer = NULL;
+#endif /* CONFIG_DCDBAS */
+ wmi_driver_register(&dell_wmi_smbios_driver);
+
if (!buffer) {
- ret = -ENOMEM;
- goto fail_buffer;
+ kfree(da_tokens);
+ return -ENOMEM;
}
-
return 0;
-
-fail_buffer:
- kfree(da_tokens);
- return ret;
}

static void __exit dell_smbios_exit(void)
{
kfree(da_tokens);
free_page((unsigned long)buffer);
+ wmi_driver_unregister(&dell_wmi_smbios_driver);
}

subsys_initcall(dell_smbios_init);
module_exit(dell_smbios_exit);

+
MODULE_AUTHOR("Matthew Garrett <mjg@redhat.com>");
MODULE_AUTHOR("Gabriele Mazzotta <gabriele.mzt@gmail.com>");
MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
+MODULE_AUTHOR("Mario Limonciello <mario.limonciello@dell.com>");
MODULE_DESCRIPTION("Common functions for kernel modules using Dell SMBIOS");
MODULE_LICENSE("GPL");
diff --git a/drivers/platform/x86/dell-smbios.h b/drivers/platform/x86/dell-smbios.h
index 45cbc2292cd3..2f6fce81ee69 100644
--- a/drivers/platform/x86/dell-smbios.h
+++ b/drivers/platform/x86/dell-smbios.h
@@ -4,6 +4,7 @@
* Copyright (c) Red Hat <mjg@redhat.com>
* Copyright (c) 2014 Gabriele Mazzotta <gabriele.mzt@gmail.com>
* Copyright (c) 2014 Pali Rohár <pali.rohar@gmail.com>
+ * Copyright (c) 2017 Dell Inc.
*
* Based on documentation in the libsmbios package:
* Copyright (C) 2005-2014 Dell Inc.
@@ -18,9 +19,10 @@

struct notifier_block;

-/* This structure will be modified by the firmware when we enter
- * system management mode, hence the volatiles */
-
+/* If called through fallback SMI rather than WMI this structure will be
+ * modified by the firmware when we enter system management mode, hence the
+ * volatiles
+ */
struct calling_interface_buffer {
u16 class;
u16 select;
@@ -28,6 +30,13 @@ struct calling_interface_buffer {
volatile u32 output[4];
} __packed;

+struct wmi_calling_interface_buffer {
+ struct calling_interface_buffer smi;
+ u32 argattrib;
+ u32 blength;
+ u8 data[32724];
+} __packed;
+
struct calling_interface_token {
u16 tokenID;
u16 location;
--
2.14.1
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